Turbine blade with tapered one-piece erosion shield



P 27, 1966 J. CALDWELL ETAL 3,275,295

TURBINE BLADE WITH TAPERED ONE-PIECE EROSION SHIELD Filed June 11, 1965 F I G. 1

10A I we I United States Patent Otfice 3,275,295 Patented Sept. 27, 1966 3,275,295 TURBINE BLADE WITH TAPERED ONE-PIECE EROSION SHIELD John Caldwell, Rugby, and Robert Hunter Telfer, Whetstone, England, assignors to The English Electric Company Limited, London, England, a British company Filed dune 11, 1965, Ser. No. 463,271 Claims priority, application Great Britain, June 12, 1964, 24,547/64 2 Claims. (Ci. 253-77) This invention relates to turbine blades.

According to the invention, in a turbine blade comprising a body portion and a shield, of a material substantially more resistant to erosion than that of the body portion, secured along a face formed on the leading edge of the body portion and profiled externally so as to be continuous with the body portion, said shield is formed in one piece.

According to a preferred feature of the invention, at least the greater part of said shield is tapered, the wider end thereof being arranged adjacent the tip of the blade.

According to another preferred feature of the invention, at least the greater part of said face on the leading edge of the body portion and the corresponding face of the tapered portion of the shield are flat.

According to yet another preferred feature of the invention, one end of the shield has a lug portion engaging a ledge formed in the body portion adjacent the tip thereof.

According to a further preferred feature of the invention, a method of making said blade includes the step of fixing the shield to the body portion by electron beam welding or by brazing.

One turbine blade incorporating preferred features of the invention will now be described by way of example and with reference to the accompanying drawings, of which:

FIG. 1 is a sectional plan view of the blade, taken on the line II of FIG. 2;

FIG 2 is an elevation of the blade; and

FIG. 3 is a general view of an erosion-resistant shield forming part of the blade.

The blade comprises a blade body of steel having a straight flat edge 11 formed (by milling or other suitable operation) at its leading edge, at the outer end of which a cut-out portion be formed so as to provide a ledge 10B. A shield 12 of erosion-resistant material, for example a cobalt chrome alloy (one typical example being the material known by the Registered Trademark Stellite 6), has a corresponding straight flat edge 13. At the outer end of the shield 12 a hook or lug 12A is formed, engaging the ledge 100 on the blade body, so as to provide strengthening against stresses which may arise in the material bonding the shield to the blade body. Such stresses may comprise thermal stresses, or dynamic stresses due to high rotational speed in service, or both.

The edge 13 and lug 12A are secured to the edge 11 and ledge 10C, respectively of the blade body 10 by electron-beam welding. Alternatively, the shield 12 may be attached by brazing or other suitable means.

The shield 12 is profiled so as to be continuous with the blade body 10 when attached thereto, and in fact constitutes the leading edge of the blade. The crosssection of the tapered portion of the shield tapers from its greatest area near the radially-outer end 10A of the blade body 10 immediately adjacent the lug 12A to a rounded thin edge at the radially-inner end 103 of the blade body, i.e. nearest the blade root.

Any suitable material may be used for the shield 12, that mentioned being only one example. The shield 12 may extend along the whole of the leading edge of the blade body 10, or along only part of it.

The lug 12A is preferably provided: but in some cases it may not be necessary, in which case the flat faces 13 and 11 will extend the full length of the shield and blade body 10 respectively.

What we claim as our invention and desire to secure by Letters Patent, is:

1. A turbine blade comprising a body portion having a fiat face formed along the leading edge thereof and a shield, formed in one piece from a material substantially more resistant to erosion than said body portion, bonded to said flat face and extending the whole length of the body portion wherein said shield is tapered to zero thickness adjacent the blade root, the wider end of the shield being at the blade tip.

2. A turbine blade according to claim 1, wherein said shield has a projecting lug portion at said wider end thereof, bonded to a transverse ledge formed at the outer end of the body portion.

References Cited by the Examiner UNITED STATES PATENTS 1,862,579 6/ 1932 Parsons et .al.

1,939,357 12/1933 Lorenzerr 159 3,148,954 9/1964 Haas 253-77 X FOREIGN PATENTS 505,912 5/ 1920 France. 195,050 7/1923 Great Britain. 309,235 4/1929 Great Britain. 3 13,907 6/1929 Great Britain. 338,683 11/1930 Great Britain. 360,230 11/ 1931 Great Britain. 160,226 5/ 1933 Switzerland.

MARTIN P. SCHWADRON, Primary Examiner.

SAMUEL LEVINE, Examiner.

E. A. POWELL, JR., Assistant Examiner. 

1. A TURBINE BLADE COMPRISING A BODY PORTION HAVING A FLAT FACE FORMED ALONG THE LEADING EDGE THEREOF AND A SHIELD, FORMED IN ONE PIECE FROM A MATERIAL SUBSTANTIALLY MORE RESISTANT TO EROSION THAT SAID BODY PORTION, BONDED TO SAID FLAT FACE AND EXTENDING THE WHOLE LENGTH OF THE BODY PORTION WHEREIN SAID SHIELD IS TAPERED TO ZERO THICKNESS ADJACENT THE BLADE ROOT, THE WIDER END OF THE SHIELD BEING AT THE BLADE TIP. 